JP6297685B2 - Method for producing separation membrane for electrochemical device and separation membrane for electrochemical device produced by the method - Google Patents

Description

  The present invention relates to a method for manufacturing a separation membrane for electrochemical devices and a separation membrane for electrochemical devices manufactured by the method, and more particularly, to a separation membrane for electrochemical devices having further improved mechanical and thermal performance. The present invention relates to a manufacturing method and a separation membrane for an electrochemical device manufactured by the method.

  This application claims priority based on Korean Patent Application No. 10-2013-0131161 filed on October 31, 2013, and all the contents disclosed in the specification and drawings of the corresponding application are incorporated in this application. The

  In addition, this application claims priority based on Korean Patent Application No. 10-2014-0150288 filed on October 31, 2014, and all the contents disclosed in the specification and drawings of the corresponding application are incorporated herein by reference. Incorporated.

  In recent years, interest in energy storage has been increasing. The field of application has expanded to mobile phones, camcorders and notebook computers, and eventually to electric vehicles and power storage, and the efforts for research and development of electrochemical devices are gradually becoming concrete.

  Electrochemical elements are the field that has received the most attention from this aspect, and among them, the development of secondary batteries that can be charged and discharged has become the focus of interest. Recently, in the development of such batteries, research and development on new electrode and battery designs are being advanced in order to improve capacity density and specific energy.

  In such an electrochemical element, it is very important to evaluate and ensure safety. The most important consideration is that the user should not be injured when the electrochemical device malfunctions. For this purpose, the safety standard strictly regulates ignition and smoke in the electrochemical device. doing. In the safety characteristics of an electrochemical element, if the electrochemical element overheats and thermally explodes or the separation membrane is penetrated, there is a high risk of explosion. In particular, the polyolefin porous substrate usually used as a separation membrane of an electrochemical element undergoes severe thermal shrinkage at a temperature of 150 ° C. or more due to material characteristics and manufacturing process characteristics including stretching. There is a problem of causing a short circuit.

  In order to solve this problem, a composite separation membrane including a porous coating layer in which a slurry containing inorganic particles or organic particles and a binder polymer is coated on at least one surface of a polyolefin porous substrate having a large number of pores is proposed. Has been. In such a composite separation membrane, the inorganic / organic particles in the coating layer coated on the polyolefin porous substrate serve as a support base that can maintain the physical form of the coating layer, and the lithium ion battery At the time of overheating, the polyolefin porous substrate is prevented from being thermally contracted.

  Referring to FIG. 1, a conventional process for manufacturing such a separation membrane is obtained by extruding a polyolefin resin composition, and by stretching the extruded resin composition to obtain a sheet-like film. Extracting a plasticizer from the separated membrane, obtaining a porous film, thermally fixing the porous film, performing primary winding / slitting on the heat-set porous film, unwinding, It consisted of applying the coating slurry, drying the coating slurry, secondary winding / slitting, and packaging the product.

  In the case of such a conventional process, the heat setting process has a limitation that it must be performed at a temperature at which the polyolefin film does not melt. In addition, after the slurry is coated on the porous substrate and dried, the structural stabilization may be lost, and thus there is a problem that it is difficult to perform an additional heat setting step.

  In addition, Japanese Patent No. 5543715 includes: i) a step of melt-kneading a polyolefin resin and a plasticizer, or a polyolefin resin, a plasticizer and an inorganic agent, and (ii) a step of stretching the obtained extrudate, (iii) A method for producing a separator for a non-aqueous electrolyte battery including a step of extracting a plasticizer or a plasticizer and an inorganic agent is disclosed. However, since this is not a method of coating a slurry such as inorganic particles after forming a porous substrate, the order of the slurry coating and the heat setting step and specific conditions thereof are not mentioned.

  Also, Korean Patent No. 10-0406690 discloses that a multi-component film used as a separation membrane for an electrochemical device provides i) a polymer support layer film; ii) a gelled polymer is dissolved in a solvent. A step of producing a gelled polymer solution; iii) forming a gelled polymer layer on one or both sides of the support layer film of step i) from the gelled polymer solution of step ii) to produce a multilayer film And iv) the multilayer film of step iii) is stretched and then heat-set. However, in this document, a gelled polymer solution is simply formed on a porous substrate to form a gelled polymer layer. A slurry containing organic particles or inorganic particles is coated to form a porous coating. The step of forming the layer is not disclosed. Further, in this document, since a gelled polymer layer is first coated on a polymer support layer film, the resulting multilayer film is stretched and heat-set, so that organic particles and / or inorganic particles are included. In the case of a composite film provided with a porous coating layer, there is a limit to application because there are problems such as cracks in the TD direction occurring in the coating layer during stretching after coating.

  The present invention has been made in view of the above problems, and the composite separation membrane on which the porous coating layer is formed is more structurally stabilized, process costs can be reduced, and yield can be improved. It aims at providing the manufacturing method of the separation membrane for chemical elements.

  However, the problem to be solved by the present invention is not limited to this, and other technical problems not mentioned here will be understood more clearly from the description of the invention described below.

In order to achieve the above object, according to one aspect of the present invention,
A step of extruding a resin composition containing a polyolefin and a plasticizer; a step of stretching the extruded resin composition to obtain a polyolefin film; and extracting the plasticizer from the obtained polyolefin film to obtain a porous polyolefin film A step of coating a slurry for forming a porous coating layer on at least one surface of the porous polyolefin film, and heat-setting the porous polyolefin film coated with the slurry to form a porous coating layer A method for producing a separation membrane for an electrochemical device is provided.

Stretching of the extruded resin composition can be uniaxially stretching at least once in the MD direction or TD direction, or biaxially stretching at least once in the MD direction and TD direction.
The temperature of the heat setting may be T _m −1 ° C. or less, where T _m is the melting point of the polyolefin.
The temperature of the heat setting may be 131 ° C to 134 ° C.
The heat setting may be performed using a heat source oriented in a direction perpendicular to the surface of the slurry coated on the porous polyolefin film.

  The polyolefin may include one or more copolymers of polyethylene, polypropylene, polybutylene, polypentene, polyhexene, polyoctene, ethylene, propylene, butene, pentene, 4-methylpentene, hexene, octene, or a mixture thereof.

The plasticizer includes paraffin oil, mineral oil, wax, soybean oil, phthalates, aromatic ethers, fatty acids having 10 to 20 carbon atoms, fatty alcohols having 10 to 20 carbon atoms, and fatty acid esters. , One or more selected from the group consisting of:
The thickness of the porous polyolefin film may be 5 to 50 μm, and the pore size and porosity may be 0.01 to 50 μm and 10 to 95%, respectively.
The slurry for forming a porous coating layer may include one or more particles among inorganic particles and organic particles, a binder polymer, and a solvent.

The binder polymer may be polyvinylidene fluoride-co-trichloroethylene (polyvinylidene fluoride-co-trichloroethylene), polymethylethylene acrylate (polymethylene acrylate) ), Polyacrylonitrile, poly (vinylpyrrolidone), poly (vinyl acetate), ethylene / vinyl acetate copolymer (polyvinyl nitrile) olefinyl-co-vinyl acetate, polyethylene oxide, cellulose acetate butyrate, cellulose acetate butyrate, cellulose acetate propionate (cellulose ethyl) Polyvinyl alcohol (cyanoethylpolyvinylcohol), cyanoethyl cellulose (cyanoethylcellulose), cyanoethyl sucrose, pullulan , Carboxymethyl cellulose (carboxyl methyl cellulose), acrylonitrile-styrene-butadiene copolymer (acrylonitrile-styrene-butadiene copolymer), it may be a polyimide (polyimide) or mixtures thereof.
The inorganic particles may be inorganic particles having a dielectric constant (relative dielectric constant) of 5 or more, inorganic particles having lithium ion transfer capability, or a mixture thereof.

The inorganic particles having a dielectric constant (dielectric constant) of 5 or more are BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), Pb. (Mg _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , SiC or a mixture thereof.

The inorganic particles having lithium ion transfer capability are lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y <3), lithium aluminum titanium. phosphate _{(Li x Al y Ti z (} PO 4) 3, 0 <x <2,0 <y <1,0 <z <3), (LiAlTiP) x O y series glass (0 <x <4,0 < y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), lithium germanium thiophosphate (Li _x Ge _y P _z S _w , 0 <x <4, 0 <Y <1, 0 <z <1, 0 <w <5), lithium nitride (Li _x N _y , 0 <x <4, 0 <y <2), SiS ₂ series glass (Li _x Si _y S) _z , 0 <x <3, 0 <y <2, 0 <z <4), P ₂ S _{It can be a 5} series glass (Li _x P _y S _z , 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof.

The organic particles are polystyrene, polyethylene, melamine resin, phenol resin, cellulose, cellulose modified, polypropylene, polyester, polyphenylene sulfide, polyaramide, polyamideimide, polyimide, a copolymer of butyl acrylate and ethyl methacrylate, or It can be a mixture of these.
The average particle size of the inorganic particles and the organic particles may be 0.001 to 10 μm independently.
The method may further include winding and slitting the composite separation membrane.

The step of coating the slurry for forming the porous coating layer may not include the step of heat setting, and the step of winding and slitting.
The method may further include wrapping the composite separation membrane that has been wound and slitted.
Moreover, according to one surface of this invention, the separation membrane for electrochemical elements manufactured by the above-mentioned manufacturing method is provided.

According to another aspect of the present invention, there is provided an electrochemical device comprising a cathode, an anode, and a separation membrane interposed between the cathode and the anode, wherein the separation membrane is a separation membrane for an electrochemical device as described above. The
The electrochemical device may be a lithium secondary battery.

  According to an embodiment of the present invention, a separation membrane is manufactured in the order of an extrusion process, a stretching process, a plasticizer extraction process, a slurry coating process, and a heat setting process, so that a conventional plasticizer extraction process and a slurry coating process are performed. The heat setting / winding and slitting / unwinding steps performed in the meantime can be dramatically omitted.

  In addition, according to an embodiment of the present invention, by introducing a heat setting process after slurry coating, the physical properties of the composite separation membrane are improved, the production cost is reduced, the quality is improved, the yield is improved, and the ultra-wide coating is realized. Various effects such as space utilization can be achieved.

  Specifically, according to one embodiment of the present invention, slurry coating is performed on a porous polyolefin film, so that heat setting is performed at a temperature higher than the conventional heat setting temperature, and mechanical and thermal performance is improved. In addition, a composite separation membrane having excellent air permeability can be provided, and the length of the heat setting oven can be reduced in a compact manner, so that space utilization, process costs, and production costs can be reduced.

  In addition, according to one embodiment of the present invention, since the heat setting step is omitted before the slurry coating step, by using the heat setting oven and the drying oven separately, Space utilization and cost savings are possible.

  Also, heat setting is performed following slurry coating to produce a composite separation membrane with a porous coating layer, so that heat applied in the heat setting process is transferred to the polyolefin film through the porous coating layer. Therefore, heat setting at a relatively high temperature is possible, and the wettability of the coating slurry with respect to the fibril structure of the polyolefin film is improved.

  Furthermore, since the heat applied in the heat setting process is transferred to the polyolefin film through the porous coating layer, the polyolefin film has fibrils having a smaller diameter, and the fibril number density (fibrilla number per unit area). Density) increases and the interface contact area with the coating slurry forming the porous coating layer increases, which makes it easier to maintain the physical form of the polyolefin film, and the thermal contraction rate of the composite separation membrane Is improved, and the peel strength of the coating layer is improved.

The following drawings attached to the specification illustrate preferred embodiments of the present invention, and together with the detailed description, serve to further understand the technical idea of the present invention. It should not be construed as being limited to the matters described in the drawings.
It is a conceptual diagram which shows the conventional process for manufacturing the separation membrane for electrochemical elements. It is a conceptual diagram which shows the manufacturing method of the separation membrane for electrochemical elements by one Example of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed to be limited to ordinary or lexicographic meanings, and the inventor himself should explain the invention in the best possible manner. It must be interpreted with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that the term concept can be appropriately defined. Therefore, the configuration described in the embodiments and drawings described in this specification is only the most preferable embodiment of the present invention, and does not represent all of the technical idea of the present invention. It should be understood that there are various equivalents and variations that can be substituted at the time of filing.

A method for producing a separation membrane for an electrochemical device according to one aspect of the present invention includes a step of extruding a resin composition containing a polyolefin and a plasticizer, and a step of obtaining a polyolefin film by stretching the extruded resin composition. Extracting a plasticizer from the polyolefin film to obtain a porous polyolefin film; coating at least one surface of the porous polyolefin film with a slurry for forming a porous coating layer; and a porous layer coated with the slurry. Heat-setting the porous polyolefin film to obtain a composite separation membrane having a porous coating layer formed thereon.
FIG. 2 is a conceptual diagram illustrating a method for manufacturing a separation membrane for an electrochemical device according to an embodiment of the present invention.

  Referring to FIG. 2, the method for manufacturing a separation membrane for an electrochemical device according to an embodiment of the present invention may further include winding and slitting the composite separation membrane that has been heat-set to obtain a final product. . In addition, the method may further include packaging the composite separation membrane that has been wound and slitted.

  In addition, the method for manufacturing a separation membrane for an electrochemical device according to an embodiment of the present invention is heat-set before the step of coating the slurry for forming a porous coating layer as compared with the conventional manufacturing method shown in FIG. And the steps of winding and slitting are not included.

Specifically, according to an embodiment of the present invention, the separation membrane is manufactured in the order of the extrusion process, the stretching process, the plasticizer extraction process, the slurry coating process, and the heat setting process, thereby the conventional process illustrated in FIG. Since the heat setting step after the plasticizer extraction step, the winding and slitting step, and the unwinding step as in the manufacturing method are not necessary, these steps can be omitted epoch-makingly.
Hereinafter, each stage will be described in detail.

  First, in the extrusion step, the polyolefin is not particularly limited as long as it is usually used in the industry. Specific examples of such polyolefins include polyethylene such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra high molecular weight polyethylene (UHMWPE), polypropylene, Examples thereof include, but are not limited to, polybutylene, polypentene, polyhexene, polyoctene, ethylene, propylene, butene, pentene, 4-methylpentene, hexene, octene, one or more copolymers, or a mixture thereof.

The plasticizer is not particularly limited as long as it is usually used in the art. Non-limiting examples of such plasticizers include phthalic acid esters such as dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and diphenyl ether. ether), aromatic ethers such as benzyl ether, local acids having 10 to 20 carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, palmitic acid alcohol, stearic acid alcohol Fatty acid alcohols having 10 to 20 carbon atoms such as oleic alcohol, palmitic acid mono-, di- or triesteral, stearic acid Saturated and non-saturated and unsaturated carbon groups of 4 to 26 carbon atoms in fatty acid groups such as no-, di- or triesteral, oleic acid mono-, di- or triesteral, linoleic acid mono-, di- or triesteral. One or two or more fatty acids in which the double bond of saturated fatty acid or unsaturated fatty acid is replaced by epoxy, the fatty acid ester-bonded with an alcohol having 1 to 8 hydroxy groups and 1 to 10 carbon atoms There are esters.
Moreover, as said plasticizer, it can be used also as a mixture containing 2 or more types of the above-mentioned component.

  The weight ratio of the polyolefin to the plasticizer may be 80:20 to 10:90, desirably 70:30 to 20:80, more desirably 50:50 to 30:70. If the weight ratio is larger than 80:20 and the content of polyolefin is increased, the porosity is reduced and the pore size is reduced, the interconnection between the pores is reduced and the permeability is greatly reduced, Processing may be difficult due to an increase in extrusion load due to an increase in the viscosity of the polyolefin solution. If the weight ratio is less than 10:90 and the content of the polyolefin decreases, the kneadability between the polyolefin and the plasticizer decreases. Thus, the polyolefin is not thermodynamically kneaded into the plasticizer and extruded in a gel form, which may cause problems such as breakage and thickness variation at the time of stretching, and the strength of the produced separation membrane may be lowered.

  In the present invention, in order to produce a composite separation membrane, first, part or all of the material is mixed using a Henschel mixer, a ribbon blender, a tumbler blender, or the like. Subsequently, it is melt-kneaded by a screw extruder such as a single screw extruder or a twin screw extruder, a kneader, a mixer, etc., and extruded from a T-die, an annular die or the like. The kneaded / extruded melt can be solidified by compression cooling, and as a cooling method, a method of directly contacting a cooling medium such as cold air or cooling water, a method of contacting a roll or press machine cooled by a refrigerant, etc. Is mentioned.

Thereafter, the extruded resin composition is stretched to obtain a polyolefin film. In this case, the stretching method may be performed by a conventional method known in the art. Non-limiting examples include MD (longitudinal direction) uniaxial stretching by a roll stretching machine and TD (transverse direction) uniaxial stretching by a tenter. And sequential biaxial stretching by a roll stretching machine and a tenter, or a combination of a tenter and a tenter, simultaneous biaxial stretching by simultaneous biaxial tenter or inflation molding, and the like. Specifically, the extruded resin composition may be uniaxially stretched one or more times in the MD direction or TD direction, or biaxially stretched one or more times in the MD direction and TD direction.
The draw ratio can be 3 times or more, preferably 5 to 10 times in the longitudinal direction and the transverse direction, respectively, and the total draw ratio (total surface magnification) can be 20 times or more, preferably 20 to 80 times.

  If the stretch ratio in one direction is less than 3 times, the orientation in one direction is not sufficient, the physical property balance between the longitudinal direction and the transverse direction is broken, and the tensile strength and the puncture strength can be lowered. Further, if the total stretch ratio is less than 20 times, unstretched may occur and pores may not be formed. If it exceeds 80 times, breakage occurs during stretching, and the shrinkage rate of the final film increases. There is.

  At this time, the stretching temperature may vary depending on the melting point of the polyolefin used, the concentration and type of the plasticizer, and preferably the stretching temperature is within a temperature range in which 30 to 80% by weight of the crystalline portion of the polyolefin in the film is melted. It is desirable to choose.

  If the stretching temperature is selected from a temperature range lower than the temperature at which 30% by weight of the crystalline portion of the polyolefin in the sheet molding is melted, the film has no softness and the stretchability is reduced. Sometimes the possibility of breakage increases and unstretching also occurs. On the other hand, if the stretching temperature is selected from a temperature range higher than the temperature at which 80% by weight of the crystal part is melted, stretching is easy, and the occurrence of unstretching is small. Variation occurs, the orientation effect of the resin is reduced, and the physical properties are greatly deteriorated. In addition, the extent to which the crystal part melts depending on the temperature can be obtained from DSC (differential scanning calorimeter) analysis of the film molding.

  Subsequently, a plasticizer is extracted from the stretched film to obtain a porous polyolefin film. Specifically, the plasticizer is extracted from the stretched film using an organic solvent and dried.

  The extraction solvent used for extraction of the plasticizer is preferably a poor solvent for polyolefin and a good solvent for plasticizer, but has a boiling point lower than that of polyolefin and quick drying. Non-limiting examples of such extraction solvents include hydrocarbons such as n-hexane and cyclohexane, halogenated hydrocarbons such as methylene chloride, 1,1,1-trichloroethane, and fluorocarbons, ethanol and isopropanol, etc. Alcohols, and ketones such as acetone and 2-butanone.

As the extraction method, all usual solvent extraction methods such as an immersion method, a solvent spray method, and an ultrasonic method can be used individually or in combination. In the extraction, the content of the residual plasticizer is preferably 1% by weight or less. If the residual plasticizer exceeds 1% by weight, the physical properties deteriorate and the permeability of the porous membrane decreases. The amount of residual plasticizer can be affected by the extraction temperature and extraction time, and the extraction temperature should be high to increase the solubility of the plasticizer and organic solvent, but consider the safety issues due to boiling of the organic solvent In this case, 40 ° C. or lower is desirable. If the extraction temperature is equal to or lower than the freezing point of the plasticizer, the extraction efficiency is greatly reduced, so it must be higher than the freezing point of the plasticizer.
Moreover, although extraction time changes with thickness of the porous polyolefin film manufactured, in the case of 10-30 micrometers thickness, 2-4 minutes are suitable.

  The thickness of the obtained porous polyolefin film is not particularly limited, but is preferably 5 to 50 μm, and the size and porosity of the pores present in the porous substrate are not particularly limited, but 0.001 to 50 μm and It is desirable that it is 10 to 99%.

  Subsequently, a slurry for forming a porous coating layer is coated on at least one surface of the porous polyolefin film. For this purpose, a slurry for forming a porous coating layer is prepared in advance, and at this time, the slurry is prepared by dispersing a binder polymer in a solvent together with one or more particles of inorganic particles and organic particles. That is, the slurry may include inorganic particles alone, organic particles alone, or inorganic particles and organic particles simultaneously.

The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are particularly those that do not undergo oxidation and / or reduction reaction within the operating voltage range of the applied electrochemical device (for example, 0 to 5 V based on Li / Li ⁺ ). Not limited. In particular, when using inorganic particles having ion transfer capability, the performance can be improved by increasing the ionic conductivity in the electrochemical element. In addition, when inorganic particles having a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolytic solution can be improved by contributing to an increase in the dissociation degree of an electrolyte salt in the liquid electrolyte, for example, a lithium salt.

  Non-limiting examples of the inorganic particles include inorganic particles having a dielectric constant of 5 or more, desirably 10 or more, inorganic particles having lithium ion transfer capability, or a mixture thereof.

Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), Pb (Mg _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ There are O ₃ , Al ₂ O ₃ , TiO ₂ , SiC or a mixture thereof.

In the present specification, “inorganic particles having lithium ion transfer capability” refers to inorganic particles containing lithium element but having a function of moving lithium ions without preserving lithium, and having lithium ion transfer capability. Non-limiting examples of lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y <3), lithium aluminum titanium phosphate ( _{li x Al y Ti z (PO} 4) 3, 0 <x <2,0 <y <1,0 <z <3), 14Li 2 O-9Al 2 O 3 -38TiO 2 -39P 2 O 5 such as a (LiAlTiP) _x O _y series glass (0 <x <4,0 <y <13), lithium lanthanum titanate _{(Li x La y TiO 3,} 0 <x <2,0 <y <3), Li 3.25 G e Lithium germanium thiophosphate such as _0.25 P _0.75 S ₄ (Li _x Ge _y P _z S _w , 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5), Li LiN nitride such as ₃ N (Li _x N _y , 0 <x <4, 0 <y <2), SiS ₂ series glass such as Li ₃ PO ₄ —Li ₂ S—SiS ₂ (Li _{x Si y S z, 0 <x} <3,0 <y <2,0 <z <4), P 2 S 5 series glass such as _{LiI-Li 2 S-P 2} S 5 (Li x P y S _z , 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof.
The organic particles contained in the slurry are advantageous in terms of air permeability, heat shrinkability, and peel strength, and have excellent binding properties with the binder polymer.

  Non-limiting examples of organic particles that can be used in the slurry for forming the porous coating layer include polystyrene, polyethylene, melamine resin, phenol resin, cellulose, cellulose modified (such as carboxymethyl cellulose), polypropylene, Polyester (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymer of butyl acrylate and ethyl methacrylate (cross-linked polymer of butyl acrylate and ethyl methacrylate, etc.), etc. And particles made of various polymers. The organic particles can be composed of two or more kinds of polymers.

  The size of the inorganic particles or organic particles is not limited, but may be independently in the range of 0.001 to 10 μm in order to form a coating layer with a uniform thickness and have an appropriate porosity.

  The binder polymer used in the slurry for forming the porous coating layer is not particularly limited as long as it can perform a function of stably fixing inorganic particles or organic particles connected to each other. Non-limiting examples include polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-co-trichloroethylene), poly (vinylidene fluoride-co-trichloroethylene), (Polybutylacrylate), polyacrylonitrile (polyacryl) lontrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide (cell), cellulose acetate (cell) acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol (cyanoethylpolypo) yvinylylcohol), cyanoethyl cellulose (cyanoethylcellulose), cyanoethyl sucrose, pullulan, dimethylmethyl cellulose, acrylonitrile styrene butadiene copolymer (e.g. These may be used alone or in admixture of two or more.

  The composition ratio of the particles of the slurry for forming the porous coating layer to the binder polymer may be, for example, in the range of 50:50 to 99: 1 or 70:30 to 95: 5 on a weight basis. If the content of the particles is too small with respect to the binder polymer, the improvement of the thermal safety of the separation membrane may be lowered, and there is not enough space formed between the particles, and the pore size and pores are not formed. The degree can be reduced and the performance of the final battery can be reduced. On the other hand, if the content of the particles is too large with respect to the binder polymer, the peel resistance of the porous coating layer can be weakened.

  As the solvent contained in the slurry, a solvent in which the particles and the binder polymer can be uniformly dispersed and can be easily removed later is desirable. Non-limiting examples of solvents that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone. (N-methyl-2-pyrrolidone, NMP), cyclohexane, water, or a mixture thereof.

The slurry for forming a porous coating layer is coated on at least one surface of a porous polyolefin film. As a specific coating method, a conventional coating method known in the art can be used. For example, Dip coating, Die coating, roll coating, comma coating can be used. Alternatively, various methods such as a mixed method thereof can be used. The porous coating layer can be selectively formed on both sides or only on one side of the porous polyolefin film.
Subsequently, the porous polyolefin film coated with the slurry is heat-set to obtain a composite separation membrane having a porous coating layer formed thereon.

  The heat setting is a process of fixing the film and applying heat to forcibly catch the film to be shrunk and remove the residual stress. A higher heat setting temperature is desirable because the shrinkage ratio is reduced. However, when the heat setting temperature is too high, the polyolefin film is partially melted, and the formed fine pores are blocked and the permeability can be lowered.

  In the present invention, after the polyolefin film is stretched, the plasticizer is extracted and then coated with the slurry for forming the porous coating layer, followed by heat setting. Unlike the process of extracting and heat-setting, heat-fixing is performed on the coated slurry instead of the polyolefin film, so that heat is not directly applied to the polyolefin film.

Therefore, compared with the conventional method, melting of the polyolefin film can be suppressed even if heat setting is performed at a high temperature. Also, since the amount of heat directly applied to the polyolefin film is reduced, the thickness of the fibril of the polyethylene substrate adjacent to the porous coating layer is made thinner than the fibril of the polyolefin film that has been heat-fixed. . Thus, since the fibril number density per unit area of the surface of the porous film adjacent to the porous coating layer is increased, an increase in interfacial contact area between the coating slurry, the glass transition temperature T _g or melting T _m of a coating slurry In the heat setting treatment in a higher temperature range, the wettability of the slurry with respect to the fibrous structure of the porous polyolefin film can be improved.
The temperature of the heat setting is desirably adjusted to T _m −1 ° C. or less, where T _m is the melting point of the polyolefin.

According to one embodiment of the present invention, when polyethylene is used as the polyolefin, the heat setting temperature may be 131 to 135 ° C., preferably 131 to 133 ° C., and the heat setting temperature satisfies such a range. In this case, the binding force (peeling strength) between the porous coating layer and the porous polyolefin film can be improved, the structural stability can be secured, and the thermal mechanical properties can be improved.
The heat setting may be performed using a heat source directed in a direction perpendicular to the surface of the slurry coated on the porous polyolefin film.

  As described above, since the high-temperature heat source is directed perpendicular to the surface of the slurry coated with the porous polyolefin film in the heat setting step, the binder polymer in the coated slurry is placed on the surface of the porous polyolefin film. On the other hand, the probability of rearrangement in the vertical direction increases. For this reason, a coating layer structure in which movement of lithium ions is easy is formed in the porous coating layer, and the lithium ions can communicate with pores formed in the porous polyolefin film. Also, the binder polymer between the particles and the binder polymer that is not completely bonded to the particles are rearranged by the recrystallization action by the high-temperature heat source, and the resistance due to the binder polymer can be greatly reduced. Thus, the tendency that the probability that the binder polymer is arranged in the vertical direction is high is not particularly well dispersed in the solvent, such as cyanoethyl polyvinyl alcohol, and it is dense on the porous polyolefin film. This is particularly effective in the case of a binder polymer that forms a film.

  The thickness of the porous coating layer thus formed is not particularly limited, but may be in the range of 0.01 to 20 μm, and the pore size and porosity are not particularly limited, but the pore size is 0. The range may be 001-10 μm and the porosity may be in the range 10-99%. The size and porosity of the pores mainly depend on the size of the particles used. For example, when particles having a particle size of 1 μm or less are used, the formed pores also have about 1 μm or less.

  In the porous coating layer, the particles are filled and in contact with each other, and are interconnected by the binder polymer to form an interstitial volume between the particles. The interstitial volume between the inorganic particles becomes an empty space and forms pores.

  That is, the binder polymer is attached to each other so as to maintain the state in which the particles are bonded to each other, for example, the binder polymer connects and fixes the particles to each other. In addition, the pores of the porous coating layer are pores formed by the interstitial volume between the particles becoming an empty space, and this is substantially due to the particle packed structure (closed packed or densely packed). It is a space limited by the particles that are in surface contact with each other. Such a pore structure is filled with an electrolyte solution to be injected later, and the electrolyte solution filled in this way is a path through which lithium ions, which are essential for operating the battery, move through the pores of the porous coating layer. Can provide.

  As described above, the separation membrane manufacturing method according to an embodiment of the present invention is different from the conventional manufacturing method shown in FIG. 1 in that the heat setting step, the winding and slitting step after the plasticizer extraction step. No unwinding process is required.

  Here, the winding process is a step of winding a composite separation membrane obtained after slurry coating and heat setting on a porous polyolefin film obtained through an extrusion / stretching / extraction step on a roller. The slitting process refers to a step of cutting unnecessary portions at both ends when winding the composite separation membrane. In the conventional method, after the heat-setting of the porous polyolefin film, an unwinding process for unwinding the wound film is necessarily required for the slurry coating through the winding and slitting processes, and after the slurry coating and drying processes. Then, after the winding and slitting process again, it finally reached the packaging stage.

  On the other hand, according to one embodiment of the present invention, the winding and slitting process is reduced from the conventional two times to one time, so that the porous polyolefin film is partially lost in the winding and slitting process. Can prevent and increase yield.

  In addition, since the unwinding process before the conventional slurry coating process and after the winding and slitting process is omitted, space utilization and process costs can be reduced. Furthermore, since the slitting process before the slurry coating step and the winding / unwinding process are not performed, a super-wide coating is possible, and scratches such as wrinkles, pinholes and scratches on the final separation membrane are possible. Occurrence is greatly reduced and uncoated areas are also reduced.

  Also, instead of the conventional heat setting step after the plasticizer extraction and the two individual heat treatment steps after the slurry coating, by improving to a single heat treatment step of the heat setting step after slurry coating, By using only one heat setting oven instead of using a drying oven and heat setting oven separately, space utilization and cost saving can be achieved.

  According to one aspect of the present invention, an electrochemical element including a cathode, an anode, and a separation membrane interposed between the cathode and the anode is an electrochemical device in which the separation membrane is the aforementioned separation membrane for an electrochemical device. Provided.

  Such an electrochemical device can be manufactured by a conventional method known in the art. For example, the electrochemical device is assembled through the above-described separation membrane between the cathode and the anode, and then the electrolytic solution. It can be manufactured by injecting.

  The electrode applied together with the separation membrane is not particularly limited, and can be manufactured in a form in which an electrode active material is bound to an electrode current collector by an ordinary method known in the art.

  Non-limiting examples of the cathode active material among the electrode active materials may include a normal cathode active material used for a cathode of a conventional electrochemical device, in particular, lithium manganese oxide, lithium cobalt oxide, It is desirable to use lithium nickel oxide, lithium iron oxide, or a lithium composite oxide combining these. Non-limiting examples of the anode active material may include conventional anode active materials used for anodes of conventional electrochemical devices, particularly lithium metal or lithium alloys, carbon, petroleum coke, active Lithium adsorbents such as activated carbon, graphite or other carbons are desirable.

  Non-limiting examples of cathode current collectors include foils made from aluminum, nickel or combinations thereof, and non-limiting examples of anode current collectors include copper, gold, nickel or There are foils made of copper alloys, or combinations thereof.

The electrolyte solution that can be used in one embodiment of the present invention is a salt having a structure such as A ⁺ B ⁻ , where A ⁺ is an alkali metal cation such as Li ⁺ , Na ⁺ , K ⁺ , or the like B ⁻ is PF ₆ ⁻ , BF ₄ ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , AsF ₆ ⁻ , CH ₃ CO ₂ ⁻ , CF ₃ SO ₃ ⁻ , N A salt containing an anion such as (CF ₃ SO ₂ ) ₂ ⁻ , C (CF ₂ SO ₂ ) ₃ ⁻ , or an ion composed of a combination thereof is propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate ( DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP) , Ethylmethyl carbonate (EMC), gamma-butyrolactone, or a mixture thereof, but not limited thereto.

  The injection of the electrolytic solution can be performed at an appropriate stage in the battery manufacturing process depending on the manufacturing process and required physical properties of the final product. That is, it can be applied before the battery is assembled or at the final stage of the battery assembly.

  As a process of applying a separation membrane according to an embodiment of the present invention to a battery, in addition to winding, which is a general process, lamination and stacking and folding processes of a separation membrane and an electrode Is applicable.

  Hereinafter, the present invention will be described in detail with specific examples. However, the embodiments according to the present invention can be modified in many other forms, and the scope of the present invention should not be construed to be limited to the embodiments described later. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

Example 1
Extruded at a temperature of 210 ° C. using high density polyethylene having a weight average molecular weight of 500,000 as polyolefin and liquid paraffin having a kinematic viscosity of 68.00 cSt as a plasticizer at a weight ratio of 35:65. The stretching temperature was 115 ° C., and the stretching ratio was 7 times each in the machine direction and the transverse direction. Then, after extracting liquid paraffin which is a plasticizer on the conditions of 2 M / min using methyllen chloride as an extraction solvent, a porous polyolefin film having an average pore size of 0.04 μm was obtained.

Thereafter, Al ₂ O ₃ particles / cyanoethyl polyvinyl alcohol (Cyano Resin CR-V, Shin-Etsu Chemical, Ltd.) / PVDF-HFP (LBG2, Arkema) having an average particle diameter of 0.5 μm as a slurry for forming a porous layer , Inc.) / Acetone were mixed and prepared to have a weight ratio of 13.5 / 0.225 / 1.275 / 85.

  The slurry is coated on one side with a thickness of 3.5 μm on one side of the porous polyolefin film that has been completed up to the plasticizer extraction step, followed by heat setting under conditions of 132.5 ° C. and 5 m / min. A separation membrane having a thickness of 14.5 μm on which a layer was formed was produced. The resulting porous coating layer of the separation membrane had an average pore size of 0.4 μm and an average porosity of 55%.

Example 2
As a slurry for forming a porous layer (PX9022, manufactured by Zeon Corporation), organic particles composed of a crosslinked polymer compound of butyl acrylate and ethyl methacrylate having an average particle diameter of 0.5 μm, a binder (polybutyl acrylate), a dispersant (carboxymethyl cellulose) ) And a solvent prepared by ultrapure water at a weight ratio of 18 / 1.5 / 0.5 / 80, coating the both sides of the porous polyethylene film with a coating thickness of 4.0 μm, and heat setting A separation membrane for an electrochemical device was produced in the same manner as in Example 1 except that the temperature was 133 ° C. The resulting porous coating layer of the separation membrane had an average pore size of 0.5 μm and an average porosity of 61%.

Comparative Example 1
After the same polyolefin film as used in Example 1 was heat-set at 130 ° C., the same slurry for forming a porous coating layer as that used in Example 1 was 3.5 μm thick. And dried under conditions of 70 ° C. and 5 M / min to produce a separation membrane for an electrochemical device.

Comparative Example 2
The same porous polyolefin film as used in Example 2 was heat-set at 130 ° C., and then the same slurry for forming a porous coating layer as used in Example 2 on both sides thereof was 4.0 μm. The film was coated to a thickness and then dried under conditions of 70 ° C. and 5 M / min to produce a separation membrane for an electrochemical device.

Comparative Example 3
After the same polyolefin film as used in Example 1 was heat-set at 130 ° C., the same slurry for forming a porous coating layer as that used in Example 1 was 3.5 μm thick. The film was further heat-set at 132.5 ° C. under the condition of 5 M / min to produce a separation membrane for an electrochemical device.

Comparative Example 4
Similar to the one used in Example 1, it was extruded at 210 ° C. and then annealed at 110 ° C. The annealed film was coated with the same porous coating layer forming slurry as used in Example 1 to a thickness of 3.5 μm, and stretched at 115 ° C. to a stretch ratio of 7 times. Thereafter, extraction was performed in the same manner as in Example 1, and further heat setting was performed under conditions of 132.5 ° C. and 5 M / min to produce a separation membrane for an electrochemical device. The separation membrane thus produced was unsuitable for use as a separation membrane because the coating layer peeled off while being stretched after coating.

Evaluation Example The aeration time, tensile strength, heat shrinkage rate and moisture content of the separation membranes for electrochemical devices according to Example 1 and Comparative Example 1 were measured. The results are shown in Table 1 below.

(1) Measurement of aeration time Time required for 100 ml of air to pass through the separation membrane at a constant pressure (0.05 MPa) using an air permeability measuring device (EG01-55-1MR, manufactured by Asahi Seiko) (sec) Was measured. The sample was measured at a total of three points, one for each of left / middle / right of the sample, and the average was recorded.

(2) Measurement of tensile strength Using a tensile strength measuring device (3345 UTM, manufactured by Instron), both ends of a separation membrane specimen (length 12 cm, width 1.5 cm) were pulled at a speed of 500 mm / min. The strength measured as the maximum value of the force that can withstand until it was cut was measured three times, and the average was recorded.

(3) Measurement of heat shrinkage Using a convection oven, the separation membrane sample (size: 50 mm × 50 mm) was stored at 120 ° C. for 60 min, and then taken out. The length was measured using a steel ruler and converted into heat shrinkage. Measurements were made at a total of 3 points, one for each of left / middle / right of the sample, and the average was recorded.

Thermal contraction rate (%) = [1− (length of the portion where contraction is most intense) / initial length)] × 100

(4) Measurement of moisture content After finishing blank test under the condition of an oven temperature of 120 ° C. using Karl Fisher (manufactured by Mettler toledo) equipment, about 0.5 to 0.6 g of inner and outer separation membranes are contained. Nitrogen gas was introduced into the vial, the extraction time was 5 minutes, and the water content was measured. Each separation membrane sample was measured at a total of 3 points, one for each of left / middle / right, and the average was recorded.

  Referring to the results shown in Table 1, when only the heat setting step is different and Example 1 using the same raw material is compared with Comparative Example 1, after extracting the plasticizer from the polyolefin film, the inorganic substance It can be seen that Example 1 in which the slurry containing particles was coated exhibits a tensile strength and a heat shrinkage ratio superior to those of Comparative Example 1.

  The performance improvement such as the improvement of the tensile strength and the reduction of the heat shrinkage ratio is performed by performing a process of heat-fixing the polyolefin film after extraction by applying the slurry to the slurry after heat-fixing. It is understood that this is because heat setting was performed at a higher temperature than the conventional method (Comparative Example 1) in which a drying operation is performed after coating.

In addition, when taking such a high heat-fixing temperature, the length of the heat-fixing oven can be further reduced, so there is an advantage of space utilization, which not only makes it possible to reduce production costs, By drying at a temperature higher than 130 ° C., the moisture content is reduced, which is advantageous for a battery sensitive to moisture.
Next, the aeration time, tensile strength, thermal shrinkage rate and moisture content of the separation membranes for electrochemical devices according to Example 2 and Comparative Example 2 were measured, and the results are shown in Table 2 below.

Referring to the results shown in Table 2, similarly to the results shown in Table 1, the separation membrane according to Example 2 that was subjected to the heat setting step after coating was coated after the heat setting step. Compared with the separation membrane of Comparative Example 2, it can be seen that the properties of tensile strength, thermal shrinkage, and moisture content are further improved.
Next, the aeration time, tensile strength, heat shrinkage rate and moisture content of the separation membranes for electrochemical devices according to Example 1 and Comparative Example 3 were measured, and the results are shown in Table 3 below.

Referring to the results shown in Table 3, in the case of Comparative Example 3, a composite separation membrane was produced on one side of an existing polyolefin film heat-set at 130 ° C. under the same coating conditions as in Example 1. In this case, since the fabric is heat-set (annealed) before slurry coating, the binding between the fibrils is already completed. If the binding between the fibrils is completed, the mechanical strength and the thermal properties are hardly improved because the rebinding between the thick fibrils is not easy even if the heat fixation is further performed at a temperature of _Tm or less later. And since the binding force of a porous coating layer and a porous polyolefin film does not improve, it is hard to show the outstanding physical property like Example 1. FIG.

  As described above, the present invention has been described with reference to the limited embodiments and drawings. However, the present invention is not limited to this, and the technology of the present invention can be obtained by those who have ordinary knowledge in the technical field to which the present invention belongs. It goes without saying that various modifications and variations can be made within the scope of the idea and the scope of claims.

Claims (16)

A method for producing a separation membrane for an electrochemical element,
Extruding a resin composition comprising a polyolefin and a plasticizer;
Stretching the extruded resin composition to obtain a polyolefin film;
Extracting the plasticizer from the obtained polyolefin film to obtain a porous polyolefin film;
Preparing a slurry for forming a porous coating layer comprising particles and a binder polymer in a composition ratio (weight basis) in the range of 50:50 to 99: 1;
Coating at least one surface of the porous polyolefin film with the slurry for forming a porous coating layer;
Heat- setting the porous polyolefin film coated with the slurry for forming a porous coating layer at a temperature of 131 ° C. to 135 ° C . ;
Ri Na and a step of obtaining a composite separator in which the porous coating layer is formed,
The manufacturing method of the separation membrane for electrochemical elements whose said polyolefin film is polyethylene .   The stretch of the extruded resin composition is uniaxially stretched one or more times in the MD direction or TD direction, or biaxially stretched one or more times in the MD direction and the TD direction. The manufacturing method of the separation membrane for electrochemical elements as described in any one of. 3. The separation membrane for an electrochemical element according to claim 1, wherein the heat setting temperature is T _m −1 ° C. (wherein T _m is a melting point of the polyolefin) or lower. Production method.   The heat setting is performed using a heat source directed in a direction perpendicular to the surface of the slurry for forming a porous coating layer coated on the porous polyolefin film. A method for producing a separation membrane for an electrochemical element according to claim 1.   The plasticizer is paraffin oil, mineral oil, wax, soybean oil, phthalic acid esters, aromatic ethers, fatty acids having 10 to 20 carbon atoms, fatty acid alcohols having 10 to 20 carbon atoms, and fatty acid esters. The method for producing a separation membrane for an electrochemical element according to any one of claims 1 to 4, comprising at least one selected from the group consisting of: The porous polyolefin film has a thickness of 5 to 50 μm,
The electrochemical device according to any one of claims 1 to 5, wherein the porous polyolefin film has a pore size and a porosity of 0.01 to 50 µm and 10 to 95%, respectively. Method for manufacturing a separation membrane.   The electricity according to any one of claims 1 to 6, wherein the slurry for forming a porous coating layer contains one or more particles of inorganic particles and organic particles, a binder polymer, and a solvent. A method for producing a separation membrane for a chemical element.   The binder polymer is polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose. Acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile styrene butadiene copolymer, polyimide or a mixture thereof The separation membrane for an electrochemical element according to claim 7 Manufacturing method.   The method for producing a separation membrane for an electrochemical element according to claim 7, wherein the inorganic particles are inorganic particles having a dielectric constant of 5 or more, inorganic particles having lithium ion transfer capability, or a mixture thereof. The inorganic particles having a dielectric constant of 5 or more are BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), Pb (Mg _1/3 ). Nb _2/3 ) O ₃ —PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O _3, characterized in that it is a TiO _2, SiC or mixtures thereof, method for manufacturing the electrochemical device for separation membrane according to claim 9. The inorganic particles having lithium ion transfer capability are lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y <3), lithium aluminum titanium. phosphate _{(Li x Al y Ti z (} PO 4) 3, 0 <x <2,0 <y <1,0 <z <3), (LiAlTiP) x O y series glass (0 <x <4,0 < y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), lithium germanium thiophosphate (Li _x Ge _y P _z S _w , 0 <x <4, 0 <Y <1, 0 <z <1, 0 <w <5), lithium nitride (Li _x N _y , 0 <x <4, 0 <y <2), SiS ₂ series glass (Li _x Si _y S) _z , 0 <x <3, 0 <y <2, 0 <z <4), P ₂ S _The electrochemical device according to claim 9, wherein the electrochemical device is a ₅ series glass (Li _x P _y S _z , 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof. Method for manufacturing a separation membrane.   The organic particles are polystyrene, polyethylene, melamine resin, phenol resin, cellulose, cellulose modified, polypropylene, polyester, polyphenylene sulfide, polyaramide, polyamideimide, polyimide, a copolymer of butyl acrylate and ethyl methacrylate, or The method for producing a separation membrane for an electrochemical element according to claim 7, which is a mixture thereof.   13. The separator for an electrochemical device according to claim 7, wherein the inorganic particles and the organic particles each independently have an average particle size of 0.001 to 10 μm. Method.   The method of manufacturing a separation membrane for an electrochemical device according to any one of claims 1 to 13, further comprising winding and slitting the composite separation membrane.   The electricity according to any one of claims 1 to 14, wherein the step of coating the slurry for forming a porous coating layer does not include a step of heat setting, a step of winding and slitting. A method for producing a separation membrane for a chemical element.   The method for manufacturing a separation membrane for an electrochemical device according to claim 15, further comprising a step of packaging the composite separation membrane after the winding and slitting.